public class Circle {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }
    public void setRadius(double radius) {
        this.radius = radius;
    }

    public double getRadius() {
        return radius;
    }

    public void calculateS() {
        double area = Math.PI * radius * radius;
        System.out.println("它的面积是" + area);
    }

    public void calculateC() {
        double circumference = 2 * Math.PI * radius;
        System.out.println("它的周长是" + circumference);
    }

    public static void main(String[] args) {
        Circle cir = new Circle(5);
        cir.calculateC();
        cir.calculateS();
    }
}
